Bile, a very bitter, alkaline, greenish-yellow to golden-brown fluid, is produced by the liver. Bile contains salts, cholesterol, lecithin, fat, various pigments and mucin. The bile secreted by the liver serves two main functions: to get rid of certain waste products and to aid in digestion by assisting in the emulsification and absorption of fats from the intestines. Normally, bile flows from glands in the liver into many tiny bile tributaries in the liver. These tributaries eventually join together to empty into a large bile duct known as the common bile duct. From the common bile duct, the bile flows into the duodenum, where it mixes with digesting food.
The bile duct provides for bile drainage between the liver and duodenum. The bile ducts, however, are prone to strictures. A stricture is the narrowing of the lumen (the space inside of a tube). A stricture in a bile duct prevents bile drainage between the liver and duodenum. The duodenum is the first part of the small intestine where the bile mixes with digesting food. When a patient has a malignant biliary stricture, the stricture may or may not be amenable to a surgical cure or bypass.
If the malignant biliary stricture is not amenable to a surgical cure or bypass, a palliative drainage procedure is required. A palliative drainage procedure is designed to prolong the life of the patient and to make the patient more comfortable when the condition of the patient is incurable. There are three principal palliative drainage options for patients with malignant biliary strictures.
The first option is external biliary drainage, in which a drainage catheter is inserted and extends percutaneously (through the skin) into the bile ducts above the stricture and functions to drain the bile externally into a bag. With external biliary drainage, a catheter, which is a hollow tube of rubber or plastic is inserted through a small hole in the skin and liver, for the purpose of discharging bile from the liver into a bag located external of the body.
The second palliative option is an external-internal stent. The external-internal stent has a percutaneous catheter extending through the biliary obstruction into the duodenum or jejunum (the portion of the small intestine extending between the duodenum and the lower portion of the small intestine), and can drain bile internally if the catheter is capped, or externally if the catheter is left uncapped. Therefore, the external-internal stent may either drain bile into a bag located externally to the body, or the external-internal stent may drain bile internally, into the duodenum or jejunum.
The third palliative option is a total internal stent. The latter is placed entirely within the liver across the biliary obstruction. All bile drainage is done internally between the liver and the duodenum. The stent is fully located internal of the body and no external access to the stent remains.
A total internal stent is usually preferable over an externally orientated stent, since the patient will not have a catheter protruding from his body, as it may tend to constantly remind him of an incurable condition. There is also less skin irritation and pain associated with the total internal stent, as externally orientated catheters are known to cause skin irritation and pain at the skin entry site. Also, there is less risk of bile bacterial colonization and cholangiolitis with an internal stent, as compared to an externally orientated stent. Cholangiolitis, which is the inflammation of the bile ducts within the liver, occurs occasionally with external orientated stents. Accordingly, it may be imperative to the patient that the usage of a total internal stent is to be the preferred palliative option.
The prior art internal stent apparatus is the CAREY-COONS.TM. soft stent biliary endoprosthesis kit, the manufacturer being Medi-Tech.RTM. of Watertown, Mass. The Carey-Coons soft stent biliary endoprosthesis kit is primarily comprised of: an internal stent; a stabilizer; a straightener; a dilator; an initial external drainage catheter; a guidewire; and an anchor button.
The Carey-Coons endoprosthesis kit functions such that the straightener inserts into and passes through both the stabilizer and internal stent. These three components are assembled as a unit functioning to telescopically slide over a guidewire internal of the body. The nylon sutures and plastic anchor are attached to a proximal end of the internal stent. The plastic anchor button secures the internal stent within the body, preventing the stent's migration. The anchor button is placed into the subcutaneous tissues, thereafter the anchor button is covered by the skin.
The Carey-Coons internal stent is inserted within the liver either through an endoscope or through a percutaneous transhepatic approach. The endoscope approach is often less traumatic and painful as compared to the percutaneous transhepatic approach. Internal stents placed endoscopically usually can be exchanged endoscopically when they occlude. The internal stent tends to occlude usually within three months of placement. However, sometimes endoscopic internal stent placement or exchange is technically not possible. When endoscopic exchange of internal stents is not possible, re-access to the biliary tract must be accomplished through the percutaneous transhepatic approach. The percutaneous transhepatic approach, however, commits the patient to hospitalization and a potentially painful procedure every time their internal stent occludes.
The Carey-Coons internal stent, through a percutaneous transhepatic approach, is deployed across the stricture in the biliary duct. The first step of this procedure is the percutaneous transhepatic insertion of a guidewire through the hepatic duct of the liver and into the biliary duct, thereafter proceeding through the biliary duct stricture and into the duodenum. The Carey-Coons three piece assembled unit is then telescopically positioned over the guidewire and slipped over the guidewire until the stent is deployed across the stricture in the biliary duct.
The physician then disengages the straightener from the stabilizer, and thereafter the straightener is extracted externally from the body. The physician then removes the stabilizer so that it is extracted externally from the body. With the guidewire still in place, the initial external drainage catheter is telescopically positioned over the guidewire and advanced over the guidewire so that the tip of the initial external drainage catheter is deployed near the internal stent. The guidewire is then removed. Thus, the initial external drainage catheter enables both the biliary tree and internal stent to be flushed and drained, thus insuring that blood and debris which result from the manipulation in the liver will not clog the internal stent. After about two days the initial external drainage catheter is removed from the body.
Migration of the stent in the biliary duct is prevented by the nylon sutures attached to the proximal end of the internal stent. These sutures are attached to a plastic anchor button which is embedded by the physician in the subcutaneous tissue under the dermis layer of the skin.
When the Carey-Coons internal stent occludes, it first must be released from the sutures before it may be removed or exchanged. In order to remove the sutures, uncovering of the plastic button embedded in the subcutaneous tissue is required. The plastic button is uncovered through a subcutaneous cutdown, which serves to avail the plastic anchor button to the physician. The sutures attaching to the plastic anchor button embedded in the subcutaneous tissue are then severed, and the plastic anchor button is thereafter removed from the subcutaneous tissue. Next, access to the biliary duct can sometimes be accomplished by slipping a dilator telescopically over the nylon sutures, using the nylon suture essentially as a guidewire to the occluded stent. The dilator enlarges the cavity in the skin and liver which connect to the biliary duct. The occluded stent is then removed from the bile duct. The occluded stent may be removed either externally through the skin or it may be pushed into the bowel, thereafter passing out with the fecal stream. Lastly, a new guidewire is slipped through the dilator until it passes through the stricture in the biliary duct. The dilator is then removed from the body by telescopically sliding it over the guidewire until it is external of the body. A new three piece Carey-Coons assembled unit is then telescopically positioned over the guidewire and slipped over the guidewire until the internal stent lies across the stricture in the biliary duct. The process to prevent migration of the stent out of the bile ducts, as set forth above, is then repeated.
Not infrequently, however, the sutures may not be strong enough to guide a dilator into the internal organs of the patient. In such instances, a brand new percutaneous transhepatic access is needed, subjecting the patient to an additional multi-step, potentially painful procedure.
Hence, there exists a need to provide for a more efficient apparatus serving to simplify the removal and exchange of internal stents.
It is therefore a primary object of the subject invention to provide for a surgical apparatus functioning to simplify the removal and exchange of internal stents.
It is a further object of the subject invention to provide a surgical means for exchanging and removing internal stents without the requirement of having to form a new cavity from the external layer of the skin to the biliary duct.
A further object of the subject invention is to provide for an apparatus having a more efficient anchoring means for stabilizing the subject invention when it is within the internal organs of the human body.